Testing system and testing method

A testing system, comprising:

• a first testing device, coupled to a first stream facing-port of a device under test and comprising a controller,
• wherein the controller is configured to transmit a testing signal to the device under test through the first stream facing-port to test a universal serial bus (USB) of the device under test, and
• the testing signal comprises a test command and the test command is configured to instruct the device under test to operate in a tunneling mode and perform a test operation to generate a data signal, wherein the test operation corresponds to a vendor command of the device under test;
• and
• a second testing device, coupled to a second stream facing-port of the device under test,
• wherein the second testing device is configured to receive the data signal through the second stream facing-port from the device under test and the data signal comprises information corresponding to a type of the second stream facing-port,
• the second testing device is configured to obtain status information of the device under test in response to the test operation to generate a testing result, and
• the controller determines whether the device under test is normal according to the testing result.